1. Field of the Invention
The present invention relates to a liquid crystal display device including an optical film for increasing a viewing angle of an image that is displayed on a liquid crystal panel.
2. Description of the Related Art
There has been a strong demand for an improvement of, in particular, vertical viewing angle characteristics of a liquid crystal display device that is provided on a mobile phone.
With a WV film that is usually used in a personal computer monitor, a vertical viewing angle cannot be increased. In order to increase the vertical viewing angle, Jpn. Pat. Appln. KOKAI Publication No. 8-122755 proposes a liquid crystal display device that includes an NH film that can compensate birefringence in a wide wavelength region.
In the liquid crystal display device with the NH film, the vertical viewing angle can be improved. However, such a problem arises that vertical and horizontal viewing angle distributions vary due to matching of optical constants (e.g. Δnd, ω,) of the panel and retardation values of the NH film.
The object of the present invention is to provide a liquid crystal display device with good display characteristics relating to vertical and horizontal viewing angles, which are obtained by optimizing the matching of retardation values of optical films.